


My Boyfriend: The Royal Scientist

by themystery424



Series: I'll Love You Even When You Forget My Name [4]
Category: Undertale, Undertale (Video Game)
Genre: Cuddling, Kissing, M/M, Meeting the Parents, The core - Freeform, angry Gaster, sensible Grillby
Language: English
Status: Completed
Published: 2017-03-30
Updated: 2017-03-29
Packaged: 2018-10-12 19:19:15
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 4
Words: 4,366
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/10497795
Author URL: https://archiveofourown.org/users/themystery424/pseuds/themystery424
Summary: After finally discovering that they are each other's soulmates, Gaster and Grillby wake up in each others arms. The cuddling doesn't last long, as the King calls, and there is a Core malfunction that Gaster must attend to. While Gaster is fixing the mess his colleagues made, Grillby is hosted by the Royal King and Queen, and gets to know a little about Gaster's past.(another part to the soulmate series :) one that's really light, too, and features some pre-Asriel Toriel and Asgore!)





	1. A Morning of Cuddling

**Author's Note:**

> Italics are signing.  
> Gaster talking is always in Wingdings.

Gaster woke up to being completely immersed in warmth. It had been his idea to have the two of them sleep without shirts on, for this reason alone. With his back pressed against Grillby’s chest, he could feel the flames twisting and turning around his spine, looping around his bones sometimes, warming him from the inside. His soul was content, always hovering near where it was hottest. It was such a nice feeling, and Gaster hoped it would never end.

The bartender behind him eventually began to move, grunting a little as he roused from sleep. Gaster sighed, rolling over in his arms, feeling his soul move so it was near his rib cage. Grillby blinked a few times to wake himself up a little more thoroughly. He glanced down at Gaster’s ribcage expectantly, and looked confused when he saw nothing. Gaster smiled, wondering if Grillby could feel it anytime his soul moved. Yeah, it was there, but invisible to prying eyes. Grillby’s eyes trailed up the skeleton, eyes focused on Gaster’s white pinpricks.

“You look so happy.” He whispered groggily. “It’s… It’s a really good look on you.” Gaster laughed softly, trying to ignore how Grillby cringed when he did. He moved his hands so they were sandwiched between them, doing his best to sign in the limited space so Grillby could understand him.

_ “I could say the same thing about you. You seem like you’re burning a bit brighter today, my dear friend.”  _ It wasn’t a lie. Grillby’s flames were burning brighter, and he was warmer. Gaster found himself  pressing his skull against Grillby’s body of flames, wrapping his arms around him so he could keep himself close. Grillby’s grip on the scientist tightened, and Gaster sighed. 

“Wingdings Gaster…” Grillby muttered quietly, and Gaster flinched instinctively at the use of his full name. “You really hate your name, don’t you?” The bartender asked, having apparently noticed how he reacted. Gaster hesitated, before slowly nodding. “I think it’s nice.” Gaster scoffed in reply.

“Yeah, maybe you do. Imagine speaking it, or, worse yet, laughing in it. Crying in it. Every noise you make, it’s that. And apparently, it hurts people.” Grillby was looking at him in confusion, and Gaster nuzzled his face back into his chest. “You can’t even understand me.”

“Can you speak English?” Grillby asked. “Or, can I learn Wingdings?” Gaster resisted laughing.

“It’s not-” He sighed, pulling back some, moving his hands so he could sign.  _ “It’s not a language you can learn dear Grillby.”  _ This soured Grillby’s expression a bit, and Gaster leaned forward, pressing his teeth to Grillby’s lips. The distraction made Grillby smile again, before kissing him back. When they parted, Gaster pressed his skull against Grillby’s chest again.

He shivered a bit as he felt Grillby’s fingers lightly caress his spine, stopping about halfway down before slowly climbing back up. Wow did that feel nice. Gaster couldn’t help but melt into the touch, his soul moving to be near it. Grillby chuckled, and Gaster grinned at the sound of the familiar rumble. The fire monster turned his head down, looking at him.

“Does that feel good?” He asked, kissing the top of his skull.

“Mhm…” Gaster responded before nodding, his voice sounding like a low purr to himself. He wondered how he sounded to Grillby, and looked up at him.  _ “When I talk, what does it sound like?” _

 

Grillby didn’t want to answer him. Gaster already seemed to hate his words, and Grillby didn’t want to make it worse. It didn’t sound pleasant. Actually, it was almost painful. Instead of answering him, he kissed him again, and that seemed to be a good enough answer as the skeleton tried to kiss back. He was getting better at manipulating his solid bone teeth to act like lips, trying to make them react in a softer, sweeter manner than what they were used to. 

Their moment was interrupted, Gaster’s cell phone ringing from the pocket of his overcoat, which had been lazily discarded last night in the excitement of sleeping in each other’s arms. Gaster made a low noise of disapproval, slowly prying himself away from Grillby, getting to his feet. As much as Grillby loved looking at the skeleton, seeing him half naked was a little unnerving. Although he had no physical mass, the drawstring sweatpants acted as if he did, hugged close to an invisible waistline. Gaster answered the phone, mumbling grumpily into it. Grillby stared at his back, able to see through to each individual rib. 

Without a second thought, Grillby got to his feet, creeping across the floor so he was behind Gaster, the scientist oblivious as he did. He wrapped his arms around his middle, fingers tracing along his rib bones. Gaster let out a small gasp, interrupting something he’d been saying. 

“Gaster?” a deep voice came through the phone. “Gaster are you alright? This is urgent. Please come to the Core as soon as possible.” Gaster replied quietly in Wingdings, leaning into Grillby’s warmth. The skeleton hung up, and neither of them moved. It felt like Grillby was absorbing Gaster, some of his flame coiling around his spine. He sensed something moving inside Gaster, and once again, Grillby tried to see it. Again, there was nothing, leaving him dumbfounded.

It took a moment for Grillby to realize Gaster was trying to sign him something,while he’d been caught up in searching for something that wasn’t there. “I’m sorry, Gaster. Could you repeat that?” The scientist huffed and mumbled something in Wingdings before signing,

_ “The Core is overheating. I need to go and deal with the problem immediately.”  _ Gaster paused, considering something. _ “Would you care to join me on this trip to Hotland? The King and Queen make lovely company, and I could show you my lab.”  _

Grillby thought it over before answering. Whether they walked through Waterfall or took a boat ride with the River Person, it meant being near huge bodies of water, something Grillby wasn’t too fond of, and he’d have to keep the bar closed down all day. 

He was about to decline, when Gaster turned in his arms, his usually white eyes glowing a faint purple, making them look bigger than what they were. Grillby could also feel that invisible force inside Gaster move so it was aligned with Grillby’s soul, making the fire monster blush blue flame as he realized what it was that he sensed moving. Gaster spoke in Wingdings as he signed, his voice the softest Grillby had ever heard;  _ “Please?” _

There really wasn’t a choice at all anymore. 


	2. The Problem With Co-Workers

**Summary for the Chapter:**

> Gaster discovers his colleague's incompetence.

The River Person was hardly ever late, though it did happen. This was one of those times. Gaster glanced at Grillby, who was dressed in thick rainwear. Underneath it all was a nice suit he owned, one that looked fantastic on him. While Gaster waited by the river, watching it flow towards the Core, Grillby understandably referred to keep his distance. Watching him brought a smile to Gaster’s face. His flames were sticking out anywhere they could, though Grillby was earnestly trying to keep them contained. Gaster laughed quietly at the sight, making the bartender blush furiously.

The River Person finally arrived, and the two stepped aboard, Gaster holding Grillby’s hand to steady him, though didn’t let go after he was on board.

“Tra la la, where to?”

“Hotland.” Grillby replied. “Quickly.” And immediately the boat began to move. They rode in silence for the most part, until, as the River Person was known to do, a cryptic remark was made. Although, this time Gaster was disappointed and a little embarrassed at the remark, as it wasn’t as hard to decipher,

“Tra la la! A ceremony is ready! Gold and violet covers the town! Tra la la!” 

Gaster glanced up at Grillby, who was blushing as well. Apparently their wedding was going to be a big deal in Snowdin.

Once they were at Hotland, Gaster bolted for the lab. He swept a keycard, running through the door the moment it was open and dashing to the computers.

“Dr. Gaster sir! It’s out of control! We have no idea what to do.” Gaster sighed, using magic to create two purple hands to sign as he mumbled quietly to himself, typing away at the keyboard. 

_ “The water, from Waterfall. What’s happened to it? The flow has just stopped.” _

“We have no idea!” An intern yelped. “W-we’ve been searching for a cause all morning!”

“You should have searched harder!” Gaster yelled in Wingdings. “I am gone a week, a week! And you can’t handle a simple cooling malfunction? What if something happens to me? Will you let the Core explode, plunge the entire Underground into hopeless darkness? Will you!” He shouted. When he turned around, all of his fellow colleagues and interns had their ears covered, eyes wide in fear. But they had understood him, since his purple hands had been signing the entire time. Gaster turned back to the screens, seeing the damage done from overheating. 

The only thing that could be done was to shut the entire Core down. 

And so Gaster did. He pulled the appropriate levers, flipping the switches and pressing the buttons necessary. The lights dimmed, before completely shutting off. The screens went dark, and the monsters were plunged into darkness.

Soon there was light, and Gaster looked over at Grillby, who was burning a gold flame on his right hand. “Come on, everyone.” He said calmly. “Let’s go.” Scared and confused, the group slowly shuffled out. Gaster made up the end of the group, and could hear the interns’ hushed whispers.

“Who is that?”

“I don’t know! How’d he get in?”

“Who cares. He’s really helping us out right now.”

“I think he came in with Dr. Gaster. Oh! Do you think-?”

“That must be him!”

“Man, he’s so lucky. I wish I was Dr. Gaster’s soulmate. He’s so smart and handsome…” So the rumors had spread to Hotland. How lovely.

Once outside, Grillby’s extra flame was turned off, no longer needed due to the light of the lava. Gaster walked to him, making his way passed the others as carefully as he could.

_ “Thank you, my dear.”  _ He signed.  _ “You really saved the day.”  _ Grillby nodded, looking around at the others.

“What now?”

_ “With the Core shut down, there is no electricity in the Underground, or cell signal, or any kind of broadcast. I need to get to the King and Queen and inform them of what’s happened. Then I need to go into the Core’s different mechanism parts, fix what’s broke, and manually reboot it, all by the light of lava, while trying not to fall in.” _

Grillby’s gold eyes watched him in concern as he rattled off all that he had to do. “What happens if you fall in?”

_ “I don’t know. And I don’t wanna find out. C’mon, let’s go to New Home.” _


	3. A Walk to New Home

**Summary for the Chapter:**

> Gaster and Grillby make their way to New Home, and Gaster leaves for the Core to mend what needs fixing, leaving Grillby with the Royals.

Grillby could honestly say he never thought he’d see Gaster that angry, his cheeks still tinted violet from the rage. Then again, he didn’t know just how much Gaster cared about the Core. As the creator, it would make sense that he would care a lot. He held the skeleton’s hand as they walked. Gaster turned his head and looked at him after some silent walking.

_ “You’re burning gold.”  _ He signed, using a pair of magic purple hands he’d manifested.  _ “Usually it’s an orange-ish color.”  _ Gaster looked at his arm.

“Well look at that. Seems that I am.” He noted, pleased. “It’s been awhile since I burned gold. I must be really happy.” This comment made Gaster grin, beaming with joy.

_ “Even through this tragedy?”  _ Grillby nodded, holding Gaster’s hand tighter.

“If it wasn’t for the dire circumstances we’re in, I’d almost say this was romantic.” He told the skeleton. Gaster pulled Grillby close, and the fire monster moved fluidly, letting Gaster move them until their bodies were flush together. Grillby didn’t stop there, brushing his lips lightly against Gaster’s teeth. Gaster responded to it happily, his cheeks flushing violet. When they parted,Gaster made a noise similar to clearing his throat.

_ “We should go. I know a shortcut.”  _ Gaster pulled Grillby along by the arm, leading him down a cavern. When they emerged, they were in front of the large stairs leading to a huge home. Gaster paused before ascending the stairs, smoothing out his clothes. Grillby followed suit, realizing he’d left his rain gear at the lab. Gaster turned and looked at him with a smile.  _ “Ready?” _

“With you by my side? Always.” Gaster laughed, or what Grillby guessed was laughing, as usually what Grillby heard resembled more of an animal in pain then joy. Gaster was smiling brightly as he looked at Grillby. He wrapped his arms around the fire monster’s neck. 

_ “You’re so cliche.”  _ Grillby caught the purple hands signing behind Gaster before his face was brought too close to the skeleton’s for him to see anything. The two kissed, right there in front of the royal home! Grillby’s soul fluttered as he stayed close to Gaster, feeling the other monster’s soul so it was closest to Grillby’s. Grillby didn’t want to part, and it seemed neither did Gaster. Until,

“W.D. Gaster! Is that you I see?” Gaster jumped apart from Grillby, his face a burning violet, consuming most of his face. The Queen was standing on the stairs, looking on the two with a gentle, mostly maternal smile. Grillby’s flames turned blue underneath his eyes, feeling a lot like a teenager getting caught by a mother. Gaster’s hands spazzed as he tried to sign in reply.

_ “I’m so sorry Toriel! We were just uh, uhm…”  _ Gaster’s hands were shaking too hard to sign now, and the Queen laughed softly.

“No need to explain yourself, my child. Come in.” She told them gently. Grillby followed Gaster’s lead, some of flames still blue. Gaster immediately went to the throne room, and Grillby decided not to follow. He stayed with Toriel, following her to the living room. He sat down on the floor while she sat in the chair, looking comfortable. She smiled at Grillby. “You seem… embarrassed.” The fire monster nodded. “Why?”

Grillby scratched the back of his neck. “I guess… It’s weird, being caught kissing in front of the King and Queen’s home. With the Royal Scientist, the King’s most trusted right hand man.” Toriel laughed in response.

“Oh it’s not weird at all. Besides, this isn’t only our home, but Gaster’s as well. As much as he tries to deny it, he always has a place here.” Grillby’s flames crackled in confusion. Toriel looked surprised, then resigned. “Of course he hasn’t told you.” She stood, walking to the bookcase and pulling a photo album down. “Asgore and I took him in… oh, twelve years ago now?” She sat beside Grillby on the floor, opening the book to a very grumpy, flustered looking Gaster, who was wearing all black. And… were his cracks always that thick?

No, Grillby realized with a laugh. It was makeup, making his cracks look twice as big as they were. And he had on leather, fingerless gloves. The coat he was wearing wasn’t his usual, classy overcoat, but a thick trench coat that was adorned with chains. 

“Did… Did Gaster go through a goth phase?” He asked, laughing as he did. Toriel smiled and nodded.

“The poor thing was insufferable. He was fifteen at the time. Of course we still loved him. Just…” She sighed. “He was so dark and whiny.” Grillby flipped through the pages, looking at the various phases of teen Gaster. When he wasn’t being punk or goth, teen Gaster had been fond of button up shirts and sweater vests. He liked science (no surprise there) and there were many photos of honoring ceremonies for his academic performance.

Grillby looked up as Asgore entered the room, his footsteps loud enough to echo off the walls. He expected Gaster to be following behind, and he was confused when the skeleton was nowhere in sight.

Toriel got to her feet, and though she was shorter than the king, she was twice as intimidating. “Where is Gaster?”

“He is tending to the Core. Hopefully he works quickly, and the power outage will end.” The Royals’ attention turned to Grillby, obviously seeking a distraction. It made Grillby wonder just how dangerous the Core was. Asgore was beaming, from what Gaster could see in the low light. “Howdy! You must be Grillby, Gaster’s soulmate!”

Grillby got to his feet, offering a handshake. “Yes, your majesty. It’s a pleasure to meet-”

The King hugged Grillby tightly, knocking Grillby’s breath out of him. “The pleasure is all mine!” He bellowed, squeezing him. Toriel was laughing quietly, and she put her hand on Asgore.

“Asgore, perhaps you should let him go. He can’t breathe.” Immediately Asgore let go, and Grillby gasped, panting for a moment as he caught his breath. “Would you like to help me with dinner, Grillby? I would appreciate another chef in the kitchen.”

“I would love to.” He responded when he caught his breath. 

“Wonderful! Follow me.” Grillby did as told, noting Asgore’s concerned expression as he did. He had no idea why the King would be worried, until he got to the kitchen.

In a small crib, there, floating in the center, was a glowing white mass, twisting around. Grillby’s flame burned gold in some places as he realized what he was looking at.

“Are you with child?” He asked softly, looking at unformed monster soul. Toriel smiled softly and nodded. 

“We are, yes… No one knows yet, not even Gaster. I trust you can keep a secret?” She said it like a request, but Gaster guessed it to be more like a demand.

“Of course, your majesty.” He responded softly. “I’ve never seen a child’s soul before… It’s not even heart shaped yet.”

“No, it isn’t.” She was soon standing beside him, a soft look in her eyes. “He is still so young, with so far to go…” She shook herself out of her stupor. “Let’s get to cooking!”


	4. A Questioning, Pie, and Time for Bed

**Summary for the Chapter:**

> The Queen serves her famous butterscotch pie, and the King and Queen have their chance to question Grillby. When they finish, Gaster returns home, sitting with his family in joy.

The three monsters sat down to eat together, all excited to be dining with one another. The King grinned, currently in the middle of telling a story about Gaster. Apparently he’d tried becoming a Shakespeare nut in his second to last year in high school.

“He could quote whole plays, line for line!” Asgore grinned. “He’d sign them, just for his amusement.” Grillby’s flame burned gold, grinning as he ate.

“Why’d he stop? Shakespeare’s a cool interest. Though not as cool as science I suppose.” He inquired. Toriel and Asgore shared a look. 

“I think… was it when he was rejected for the play?” Asgore asked his wife, who nodded grimly, looking steamed.

“They said the part wouldn’t be given to a mute.” She said, bitter. “Oh I was furious.” 

“I would be too.” Grillby agreed. There was an easy silence for a while, before Asgore cleared his throat.

“So. Do you plan on working at the bar for the rest of your life?” The King asked casually. Grillby watched him as he ate, confused by the question.

“I planned on it. It’s a stable income, and it’s doing something I love.” He replied, and Asgore nodded.

“It’s good that you think that way. Keep your passions alive in your heart.” The King smiled. “And it helps that it is a stable income.” 

“What’s your home like?” Toriel cut in. “Do you live in a house or an apartment?” Grillby turned, looking at her now. It took a moment, but he realized what was happening. He was being questioned.

“A small house, across the street from the bar.” Grillby replied. “It’s cozy.”

“Not a lot of room, I’m guessing.” Toriel sounded concerned. “Are you thinking of moving some place bigger, after you’re married?” Grillby’s flames turned blue under his eyes, blushing furiously now.

“Well we haven’t really discussed anything yet… We only just found out yesterday.”

“Really?” Asgore looked at him incredulously. “Gaster called to ask about soulmates the morning after he arrived at Snowdin.” Grillby’s blush only got worse. Gaster had known since  _ then _ ? And he hadn’t said anything at all? 

“I… O-oh.” He stuttered in response. “That uh, I-I don-”

“Have you ever considered children?” Toriel asked suddenly. “Not that it’s necessary, I am only curious.” 

“Maybe one, but-”

“Violet and gold are fine colors together.” Asgore cut in. “Loyal, royal colors. Very power, when working together.”

“Most complimentary colors are.” Toriel agreed. “Yes, I think you will make a fine couple. Although,” The Queen’s pleasant demeanor fell, and she locked eyes with Grillby. “If you hurt him for whatever reason, remember who his guardians are.” Grillby glanced at the King, who was looking just as grim as his wife. He swallowed hard before bowing his head some.

“Of course, your majesties.” Grillby told them. “Although I have no intentions of hurting him. I... love him.” He confessed quietly. This pacified both royals, who were now smiling.

“Dessert, Grillby? I have made butterscotch pie.” Toriel offered sweetly, and Asgore grinned in excitement.

“Oh it is so good! You must have a slice.” 

Grillby nodded, smiling, hoping he seemed a little more at ease than what he was. The stark reminder of just how powerful they were had startled Grillby, but he didn’t want them to worry. “That sounds nice, thank you.” 

As Toriel got to her feet, the lights turned on, washing out the candles with artificial light, and she and Asgore grinned.

“Ah, that’s better. Asgore, dear? Could you move our son’s soul out of the kitchen and to his room? Gaster will be here soon.” Asgore complied, and Grillby stayed where he was, soul fluttering in his chest as he eagerly awaited Gaster’s return.

 

Gaster stood in front of the Royal home with a sigh. It was his home, too, although he denied it. After fixing the Core, and the Waterfall irrigation blockage, Gaster hoped Toriel had some butterscotch pie because really, he just wanted to feel at home once again. Sleep in his bed, be surrounded by his family.

And Grillby.

Gaster had forgotten about Grillby, and his soul melted at the thought of being in Grillby’s arms once again. Warm from the inside out, his soul close to Grillby’s as they laid together, breathed together. He climbed the stairs quickly, taking two at a time as he did. He walked in, smiling as he did. The smell of butterscotch pie filled his senses, and his soul soared. 

“I’m home!” He called out, knowing no one would understand, but wanting to make his presence known.

“In here, my child.” Toriel called out, and Gaster followed her voice to the dining room. Across from Grillby was a vacant seat, a piece of butterscotch pie sitting there, waiting for him. He was barely sitting in his seat, when Grillby spoke up.

“How was it? Are you alright?” Gaster had a bite of pie before answering. God how he missed this. He missed Toriel and Asgore. And seeing as they had no children to call their own, Gaster really needed to make an effort to visit more. He’d gotten through half his slice before he remembered Grillby’s questions. He set his fork down to sign.

_ “It went very well. All according to plan. Got the Core running again, and came here. Besides being exhausted, I’m fine.”  _ Gaster finished his pie and leaned back in his chair, sighing contently.  _ “Does this mean I can go back to work? After the others almost destroyed the Core, was it really such a good idea to send me on vacation?”  _ He signed to Asgore.

The King smiled before answering. “You still are taking the next week off, Gaster.”

_ “Come on! Please?”  _ Gaster was whining, even if signing left no room for his tone to get through.

“No my child.” Toriel piped up, and Gaster turned to her, not to fight, but to listen. “I’m sorry, but you have been working yourself to the  _ bone  _ and I can not stand by it any longer.” There was a smile on Toriel’s face, and Gaster’s eyes glowed violet.

_ “It’s good to know you  _ goat  _ my back, Toriel.”  _ He signed in return. The queen laughed, eyes bright as she did. Grillby groaned, and Asgore patted the fire monster on the back. 

“You learn to love it.” He reassured Grillby, who simply shook his head.

“Oh Gaster, we better stop. Your soulmate is looking pretty  _ steamed.”  _ Toriel grinned.

_ “Really? Cause I think he’s downright  _ smokin’ _.”  _ The two erupted in laughter, Gaster so caught up in the moment he didn’t notice Grillby or Asgore flinch from the sound. When the laughter faded, Gaster let out a long, loud yawn, his eye sockets half closed. 

“Oh child, I think it’s time for you to sleep.” Gaster nodded, laying his head on the table. Grillby got to his feet, walking around the table and carefully picking up the skeleton. Gaster snuggled into Grillby’s warmth, unable to hear him as he spoke to Toriel. Then Grillby was moving, walking down the hall. He stopped in front of a room with a sign hanging on it, reading ‘Room under Renovations’. When Grillby stopped, Gaster poked his head out, then smiled.

“My room…” He said quietly, before repeating himself in sign. Grillby nodded before stepping in. The scientist was poured onto the twin sized bed, and immediately he latched onto the sheets, finding their familiarity comforting. He eased himself over, making room for Grillby, who looked skeptical.

“Gaster, are we both going to fit on that?” He asked. “I don’t want to make you uncomfortable.” Gaster nodded, and Grillby sighed. The fire monster laid down carefully, pulling the skeleton close. Gaster snuggled into him, feeling his soul move so it was nearest Grillby’s own soul.

“Goodnight, Grillby. I love you.” He said softly, just before drifting off.

 

Grillby hadn’t understood Gaster’s final words before the scientist fell asleep, though he wished he had. After he was sure Gaster was out for the night, he kissed the top of his head and closed his own eyes.

“Goodnight, Wingdings Gaster… I love you.”


End file.
